Inconsistent validation results in BooleanField

[warownia1]

BooleanField#validate() have inconsistent behaviour when dealing with false value:

default	provided	result
none	none	none
none	false	none
none	true	true
false	none	false
false	false	false
false	true	true
true	none	true
true	false	true
true	true	true

The result should consistently be none when the value is missing or false but explicitly setting the value to false explicitly when default is true should result in none as well.